.popup {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  background-color: rgba(0, 0, 0, .5);
  display: flex;
  align-items: center;
  overflow: hidden;
  height: 0;
  opacity: 0;
  transition: height 0s .7s, opacity .7s 0s;
}